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1.  Co-crystals of 3-de­oxy-3-fluoro-α-d-glucopyran­ose and 3-de­oxy-3-fluoro-β-d-glucopyran­ose 
3-De­oxy-3-fluoro-d-glucopyran­ose crystallizes from acetone to give a unit cell containing two crystallographically independent mol­ecules. One of these mol­ecules (at site A) is structurally homogeneous and corresponds to 3-de­oxy-3-fluoro-β-d-glucopyran­ose, C6H11FO5, (I). The second mol­ecule (at site B) is structurally heterogeneous and corresponds to a mixture of (I) and 3-de­oxy-3-fluoro-α-d-glucopyran­ose, (II); treatment of the diffraction data using partial-occupancy oxygen at the anomeric center gave a high-quality packing model with an occupancy ratio of 0.84:0.16 for (II):(I) at site B. The mixture of α- and β-anomers at site B appears to be accommodated in the lattice because hydrogen-bonding partners are present to hydrogen bond to the anomeric OH group in either an axial or equatorial orientation. Cremer–Pople analysis of (I) and (II) shows the pyranosyl ring of (II) to be slightly more distorted than that of (I) [θ(I) = 3.85 (15)° and θ(II) = 6.35 (16)°], but the general direction of distortion is similar in both structures [ϕ(I) = 67 (2)° (B C1,C4) and ϕ(II) = 26.0 (15)° (C3 TB C1); B = boat conformation and TB = twist-boat conformation]. The exocyclic hy­droxy­methyl (–CH2OH) conformation is gg (gauche–gauche) (H5 anti to O6) in both (I) and (II). Structural comparisons of (I) and (II) to related unsubstituted, de­oxy and fluorine-substituted monosaccharides show that the gluco ring can assume a wide range of distorted chair structures in the crystalline state depending on ring substitution patterns.
PMCID: PMC3089378  PMID: 21051824
2.  Phenyl 2-amino-N,6-O-dibenzyl-2,3-N,O-carbonyl-2-de­oxy-1-thio-β-d-glucopyran­oside 
In the crystal structure of the title compound, C27H27NO5S, the pyran­ose ring adopts a 4 C 1 chair conformation with puckering parameters Q = 0.639 (2) Å, θ = 174.11 (18) and ϕ = 256 (2)°. The presence of the 2,3-trans-oxazolidinone fixes the conformation of the pyran­ose ring. The phenyl group attached to the S atom and the benzyl group bonding to the N atom are each disordered over two positions with site occupancies of 0.624 (3):0.376 (3) and 0.526 (3):0.474 (3), respectively. An inter­molecular O—H⋯O hydrogen bond is observed.
PMCID: PMC2959351  PMID: 21201084
3.  1-O-Acetyl-3,4,6-tri-O-benzyl-2-C-bromo­methyl-2-de­oxy-α-d-glucopyran­ose 
In the title compound, C30H33BrO6, the pyran­ose ring adopts a chair conformation. Two of the O-benzyl phenyl rings lie almost perpendicular to C/C/C/O plane formed by the ring atoms not attached to these O-benzyl phenyl rings, and form dihedral angles of 85.1 (2) and 64.6 (2)°, while the third O-benzyl phenyl ring is twisted so that it makes a dihedral angle 34.9 (2)° to this C/C/C/O plane. This twist is ascribed to the formation of an S(8) loop stabilized by a weak intra­molecular C—H⋯O hydrogen bond.
PMCID: PMC3588367  PMID: 23476454
4.  4-(Dimeth­oxy­meth­yl)phenyl 2,3,4,6-tetra-O-acetyl-β-d-glucopyran­oside 
The enanti­omerically pure title compound, C23H30O12, crystallizes in the chiral space group P212121. The O-acetyl­ated-glucopyran­oside moiety adopts a chair conformation. Numerous C—H⋯O inter­actions as well as a C—H⋯π inter­action are present in the crystal structure.
PMCID: PMC3344139  PMID: 22606142
5.  2,4-Bis(2-eth­oxy­phen­yl)-7-methyl-3-aza­bicyclo­[3.3.1]nonan-9-one 
The crystal structure of the title compound, C25H31NO3, exists in a twin-chair conformation with an equatorial orientation of the ortho-eth­oxy­phenyl groups. According to Cremer and Pople [Cremer & Pople (1975 ▶), J. Am. Chem. Soc. 97, 1354–1358], both the piperidone and cyclo­hexa­none rings are significantly puckered with total puckering amplitutdes Q T of 0.5889 (18) and 0.554 (2) Å, respectively. The ortho-eth­oxy­phenyl groups are located on either side of the secondary amino group and make a dihedral angle of 12.41 (4)° with respect to each other. The methyl group on the cyclo­hexa­none part occupies an exocyclic equatorial disposition. The crystal packing is stabilized by weak van der Waals inter­actions.
PMCID: PMC3120546  PMID: 21754845
6.  Ethyl 3,6-di-O-benzyl-2-de­oxy-N-phthalimido-1-thio-β-d-glucopyran­oside 
In the title compound, C30H31NO6S, the plane of the N-phthalimido group is nearly orthogonal to the least-squares plane of the sugar ring (defined by atoms C2, C3, C5 and O5 using standard glucose nomenclature), making a dihedral angle of 72.8 (1)°. The thio­ethyl group has the exo-anomeric conformation. The hy­droxy group forms an inter­molecular hydrogen bond to the O atom in the sugar ring, generating [100] chains. There are four close π–π contacts with centroid–centroid distances less than 4.0 Å, all with dihedral angles between the inter­acting π systems of only ≃ 8°, supporting energetically favourable stacking inter­actions.
PMCID: PMC3011472  PMID: 21589536
7.  Ethyl 4,6-O-benzyl­idene-2-de­oxy-N-phthalimido-1-thio-β-d-glucopyran­oside 
In the title compound, C23H23NO6S, the plane of the N-phthalimido group makes a dihedral angle of 67.4 (1)° with the least square plane of the sugar ring defined by the C2, C3, C5 and O5 atoms using standard glucose nomenclature. The thio­ethyl group has the exo-anomeric conformation. In the crystal, inter­molecular hydrogen bonds involving the hy­droxy groups and the carbonyl O atoms of adjacent N-phthalimido groups form chains parallel to the b axis. The chains are further stabilized by C—H⋯π inter­actions.
PMCID: PMC3011798  PMID: 21589535
8.  A second monoclinic polymorph for 3-amino-1-(4-meth­oxy­phen­yl)-9,10-dihydro­phenanthrene-2,4-dicarbonitrile 
The title compound, C23H17N3O, has been previously described in a monoclinic P21/c polymorph with Z = 4 [Asiri, Al-Youbi, Faidallah, Ng & Tiekink (2011). Acta Cryst. E67, o2449]. In the new monoclinic P21/n form, with Z = 8, there are two independent mol­ecules, A and B, in the asymmetric unit. In both mol­ecules, the cyclo­hexa-1,3-diene ring has a screw-boat conformation, whereas it is a distorted half-chair in the original polymorph. There is a fold in each mol­ecule, as indicated by the dihedral angle between the benzene rings of the 1,2-dihydro­naphthalene and aniline residues of 33.19 (10)° (mol­ecule A) and 30.6 (10)° (mol­ecule B). The meth­oxy­benzene ring is twisted out of the plane of the aniline residue to which it is connected [dihedral angles = 49.22 (10) and 73.27 (10)°, in A and B respectively]. In the crystal, the two independent mol­ecules self-associate via N—H⋯N hydrogen bonds, generating a 12-membered {⋯HNC3N}2 synthon. These are connected into a supra­molecular tape in the (-101) plane by N—H⋯O(meth­oxy) inter­actions. In the P21/c polymorph, supra­molecular layers are formed by N—H⋯N and N—H⋯O inter­actions.
PMCID: PMC3344100  PMID: 22606103
9.  2,2,5,7,8-Penta­methyl­chroman-6-yl 2,3,4,6-tetra-O-acetyl-α-d-glucopyran­oside from synchrotron data 
The crystal structure of the title compound, C28H38O11, solved and refined against synchrotron diffraction data, contains two formula units in the asymmetric unit. In both mol­ecules, the dihydro­pyran ring along with its methyl substituents is disordered and adopts two alternative half-chair conformations. The occupancy of the major conformers of the two mol­ecules refined to 0.858 (5) and 0.523 (5).
PMCID: PMC3052099  PMID: 21522460
10.  3,4-Dicyano­phenyl 2,3,4,6-tetra-O-acetyl-α-d-glucopyran­oside 
The title compound, C22H22N2O10, was prepared by the glycosidation method through nitrite displacement on substituted nitro­phthalonitrile. The mol­ecule contains a benzene ring, two nitrile groups and an acetyl-protected d-glucose fragment which adopts a chair conformation. The absolute configuration was determined by the use of d-glucose as starting material. All substituents of the protected sugar are in equatorial positions, with the exclusive presence of the α-anomer. The crystal packing is stabilized by C—H⋯O and C—H⋯N hydrogen-bonding inter­actions.
PMCID: PMC2915021  PMID: 21200940
11.  4-Formyl­phenyl 2,3,4,6-tetra-O-acetyl-β-d-glucopyran­oside 
The pyran­oside ring in the title compound, C21H24O11, has a chair conformation with the substituted benzene ring occupying an equatorial position. The crystal packing is dominated by C—H⋯O inter­actions that lead to the formation of supra­molecular layers in the ab plane.
PMCID: PMC3099765  PMID: 21754109
12.  Isopropyl 2,3,4,6-tetra-O-acetyl-β-d-glucopyran­oside 
The title compound, C17H26O10, was formed by a Koenigs–Knorr reaction of 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide and propan-2-ol. The central ring adopts a chair conformation. The crystal does not contain any significant inter­molecular inter­actions.
PMCID: PMC3569224  PMID: 23424447
13.  n-Propyl 2,3,4,6-tetra-O-acetyl-β-d-glucopyran­oside 
The title compound [systematic name: (2R,3R,4S,5R,6R)-2-(acet­oxy­meth­yl)-6-propoxytetra­hydro-2H-pyran-3,4,5-triyl triacetate], C17H26O10, was formed by a Koenigs–Knorr reaction of 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide and n-propanol. The central ring adopts a chair conformation. The crystal does not contain any significant inter­actions such as hydrogen bonds.
PMCID: PMC3569225  PMID: 23424448
14.  3-(1-Adamant­yl)-6-methyl-3-(3-methyl­benz­yl)isochroman-1-one 
In the title compound, C28H32O2, the oxanone ring adopts distorted half-boat conformation with the following Cremer and Pople puckering parameters: Q = 0.619 (2) Å, θ = 0.75 (19) and ϕ = 172 (13)°. The dihedral angle betwen two benzene rings is 21.32 (7)°. The adamantane unit consists of three fused cyclo­hexane rings in classical chair conformations, with absolute values of C—C—C—C torsion angles in the range 57.5 (2)–60.9 (2)°. Weak inter­actions of the type C—H⋯O link mol­ecules of each enanti­omer into chains parallel to the b axis and lying about inversion centers. The crystal packing is also stabilized by inter­molecular π-π stacking inter­actions [centroid–centroid distance of 3.8566 (11) Å].
PMCID: PMC2969547  PMID: 21583062
15.  15α,20β-Dihydr­oxy-6β-meth­oxy-6,7-seco-6,20-ep­oxy-1,7-olide-ent-kaur-16-ene 
The title compound, C21H30O6, a natural ent-kaurane diterpenoid, was obtained from the medicinal plant Isodon serra. The five rings in the mol­ecule exhibit the expected cis and trans junctions. The three six-membered rings adopt chair, twist-boat and boat conformations, while two five-membered rings adopt envelope conformations. There are two mol­ecules in the asymmetric unit, related by a non-crystallographic twofold screw axis; the main difference is in the different degrees of distortion of ring B. In the crystal, the mol­ecules are linked by inter­molecular O—H⋯O hydrogen bonds, forming chains along the b axis.
PMCID: PMC2984011  PMID: 21580740
16.  4a-Hy­droxy-9-(2-meth­oxy­phen­yl)-4,4a,5,6,7,8,9,9a-octa­hydro-3H-xanthene-1,8(2H)-dione 
In the title compound, C20H22O5, an S(6) ring motif is formed by an intra­molecular C—H⋯O hydrogen bond, which contributes to the stabilization of the mol­ecule. In the xanthene system, the cyclo­hexane ring adopts a chair conformation, the cyclo­hexene ring adopts a half-boat conformation and the tetra­hydro­pyran ring adopts a half-chair conformation. The mean plane of the four essentially planar atoms of the tetra­hydro­pyran ring [r.m.s deviation = 0.092 (1) Å] forms a dihedral angle of 64.13 (6)° with the mean plane of the meth­oxy­phenyl group. In the crystal, inter­molecular O—H⋯O and weak C—H⋯O hydrogen bonds link mol­ecules into chains along the a axis, which are further stabilized by C—H⋯π inter­actions.
PMCID: PMC3050262  PMID: 21522746
17.  3-Ethyl-8-meth­oxy-4-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranos­yloxy)quinolin-2(1H)-one 
The structure of the title compound, C26H31NO12, contains an essentially planar quinoline skeleton, with the maximum deviation from the best plane being 0.055 (2) Å, and an oxane ring in a classical chair conformation with the following Cremer and Pople puckering parameters: Q = 0.586 (2) Å, θ = 11.5 (2)° and ϕ = 309.4 (10)°. One acetyl group displays rotational disorder with occupancies of 0.634 (8):0.366 (8). The crystal packing is stabilized by N—H⋯O hydrogen bonds, which link mol­ecules into chains along the a axis. The packing is further stabilized by weak C—H⋯O interactions. The absolute configurations on the carbons in the oxane ring correspond to those of the commercial starting material and are unchanged in the well known mechanism of the Koenigs–Knorr synthesis.
PMCID: PMC2979627  PMID: 21579419
18.  5-{[(3R,5aS,6R,8aS,9R,10S,12R,12aR)-3,6,9-Trimethyl­perhydro-3,12-ep­oxy-1,2-dioxepino[4,3-i]isochromen-10-yl]oxymeth­yl}benzene-1,3-diol 
The title compound, C22H30O7, is a fused five-ring system that is of inter­est for its anti­cancer and anti­malarial activity. The six-membered C6 and C5O rings display chair conformations. The six-membered C3O3 ring containing the ether and per­oxy functionalities has a distorted boat conformation, with a C—O—O—C torsion angle of 42.6 (1)° for the per­oxy group. The seven-membered C6O ring has a distorted boat-type conformation, while the seven-membered C5O2 ring has a very distorted chair-type conformation. The structure contains inter­molecular O—H⋯O and O—H⋯(O,O) bonds that link the mol­ecules into sheets parallel to the (100) planes.
PMCID: PMC2968296  PMID: 21581957
19.  10a-Hy­droxy-9-(4-meth­oxy­phen­yl)-3,4,5,6,7,8a,9,10a-octa­hydro-1H-xanthene-1,8(2H)-dione 
In the title compound, C20H22O5, the tetra­hydro­pyran, cyclo­hexene and cyclo­hexane rings of the xanthene ring system adopt half-chair, half-boat and chair conformations, respectively. The mean plane of the four roughly planar atoms of the tetra­hydro­pyran ring (r.m.s. deviation = 0.111 Å) forms a dihedral angle of 82.91 (4)° with the meth­oxy­benzene group. In the crystal, mol­ecules are linked via O—H⋯O and C—H⋯O hydrogen bonds into sheets lying parallel to the ac plane. The crystal is further consolidated by weak C—H⋯π inter­actions.
PMCID: PMC3414299  PMID: 22904832
20.  (7R,8S,9S,12S)-1-Benz­yloxy-13,14-didehydro-12-hy­droxy-2,13-dimeth­oxy-N-methyl­morphinane 
In the title compound, C26H31NO4, a sinomenine derivative, the angle between the two aromatic rings is 53.34 (4)°. The N-containing ring is in a chair conformation, while the other two non-planar rings are in a half-boat conformation. In the crystal, mol­ecules are linked by O—H⋯N inter­actions into a C(8) chain along [100].
PMCID: PMC3201304  PMID: 22058779
21.  1-(2-Hy­droxy­eth­yl)-4-{3-[(E)-2-(trifluoro­meth­yl)-9H-thioxanthen-9-yl­idene]prop­yl}piperazine-1,4-diium bis­(3-carb­oxy­prop-2-enoate) 
In the title salt, C23H27F3N2OS+·2C4H3O4 −, a non-merohedral twin [ratio of the twin components = 0.402 (1):0.598 (1)], the –CF3 group is disordered over two sets of sites with occupancy factors in the ratio 0.873 (2):0.127 (2). The dihedral angle between the two outer aromatic rings of the 9H-thioxanthene unit, whose thio­pyran ring has a screw-boat conformation, is 33.01 (9)°. The diprotonated piperazine ring adopts a chair conformation. In the crystal, inter­molecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds between neighboring mol­ecules form zigzag chains along the a axis and contribute to the stabilization of the packing.
PMCID: PMC3213470  PMID: 22091049
22.  Redetermination of 1,3-diammonio-1,2,3-tride­oxy-cis-inositol dichloride 
The crystal structure of the title compound, C6H16N2O3 2+·2Cl−, has been reported previously by Palm [Acta Cryst. (1967 ▶), 22, 209–216] from Weisenberg camera data, with R1 = 10.5%, isotropic refinement of non-H atoms and H atoms not located. We remeasured a data set of the title compound and present a more precise structure determination. The asymmetric unit contains two unique 1,3-diammonio-1,2,3-tride­oxy-cis-inositol cations and four Cl− counter-ions. The cyclo­hexane rings of both inositol cations adopt chair conformations with two axial hy­droxy groups. An extended network of hydrogen bonds is formed. The four chloride counter ions are hydrogen bonded to the hydroxy and ammonium groups of the cations by N—H⋯Cl and O—H⋯Cl interactions. The cations are aligned into wavy layers by cation⋯cation interactions of the form N—H⋯O(ax), N—H⋯O(eq) and O(ax)—H⋯O(eq). Intramolecular hydrogen bonding between the axial hydroxy groups is, however, not observed.
PMCID: PMC3344537  PMID: 22590299
23.  6-Azido-6-de­oxy-α-l-galactose (6-azido-l-fucose) monohydrate 
Although 6-azido-6-de­oxy-l-galactose in aqueous solution is in equilibrium between the open-chain, furan­ose and pyran­ose forms, it crystallizes solely as 6-azido-6-de­oxy-α-l-galactopyran­ose monohydrate, C6H11N3O5·H2O, with the six-membered ring adopting a chair conformation. The structure exists as hydrogen-bonded chains, with each mol­ecule acting as a donor and acceptor of five hydrogen bonds. There are no unusual crystal packing features and the absolute configuration was determined from the use of 1-azido-1-de­oxy-d-galactitol as the starting material.
PMCID: PMC2962088  PMID: 21203271
24.  8β-Acet­oxy-14α-benzo­yloxy-N-methyl-13β,15α-dihy­droxy-1α,6α,16β-trimeth­oxy-4β-(meth­oxy­meth­yl)aconitane: hypaconitine isolated from ‘fuzi’ 
The title compound, C33H45NO10, has an aconitine carbon skeleton with four six-membered rings and two five-membered rings. The five-membered rings adopt envelope configurations and the six-membered N-containing heterocyclic ring displays a chair conformation. Two intra­molecular O—H⋯O hydrogen bonds occur.
PMCID: PMC3009068  PMID: 21588985
25.  2,4-Bis(4-eth­oxy­phen­yl)-7-methyl-3-aza­bicyclo­[3.3.1]nonan-9-one 
The mol­ecule of the title compound, C25H31NO3, exists in a twin-chair conformation with an equatorial orientation of the 4-eth­oxy­phenyl groups, as observed for its ortho isomer [Parthiban, Ramkumar, Park & Jeong (2011b ▶), Acta Cryst. E67, o1475–o1476]. The methyl and 4-eth­oxy­phenyl groups are also equatorially oriented on the bicycle, as in the ortho analogue. In particular, although the cyclo­hexa­none ring deviates from an ideal chair, the piperidone ring is closer to an ideal chair, whereas in the ortho isomer both rings are significantly puckered and deviate from ideal chairs. The 4-eth­oxy­phenyl groups on both sides of the secondary amine group are oriented at an angle of 26.11 (3)° with respect to each other, but the 2-eth­oxy­phenyl groups in the ortho isomer are oriented by less than half this [12.41 (4)°]. In contrast to the absence of any significant inter­actions in the crystal packing of the ortho isomer, the title compound features N—H⋯O inter­actions, linking the mol­ecules along the b axis.
PMCID: PMC3297850  PMID: 22412653

Results 1-25 (62483)